The present invention relates generally to storage systems and, more particularly, to methods and apparatus for controlling data volume creation at a data storage system with dynamic chunk allocation capability.
To reduce wasted physical blocks in a data volume, dynamic chunk allocation capability is adopted in a storage system. This type of storage system has special data volumes, which means that the data volumes have no physical block initially. The storage system allocates a chunk from a chunk pool when the data volumes receive a write command and a chunk has not been allocated to the appropriate segment as specified in the write command yet. The special data volumes, referred to herein as “dynamic chunk allocation volumes (DCAVs),” are created with no chunk consumption. Therefore a huge number of DCAVs may be created at once. For example, in the case of a huge number of virtual server deployment, the huge number of DCAVs are created and associated. However the huge number of DCAVs are used (e.g., to install OS and application software from host computers) concurrently thereafter, and the chunks are consumed rapidly. As a result of rapid consumption of the chunks, the storage system must be halted in a short time.
Methods of dynamic chunk allocation capability in storage systems are disclosed, for example, in US2007/0234109 and U.S. Pat. No. 6,836,819. More specifically, these references disclose methods for issuing an alert when the number of used chunks exceeds a predetermined threshold. However, they do not disclose any methods and apparatuses for controlling a data volume creation in accordance with the number of used/unused chunks and/or capacity growth information.